Piston ring



Patented Apr. l, i941 UNITED STATES PATENT UFFICE t I 2,236,121 i I i PISTON RING Ralph R. Teetor, Hagerstown, land., assignor to The Perfect Circle Company, Hagerstown, Ind., a corporation of Indiana Application December 22, 1939, Serial No."310,480 9 Claims. (Cl. 309-45) My invention relates to piston rings for internal combustion engines.

More particularly, my Ainvention relates to improvements in the type of ring which comprises a pair of thin, at, split rails adapted to engage the'cylinder wall, and a spacer-expander adapted to space the rails axially apart and to expand the rails radially.

The principal objects of my invention are to provide an improved spacer-expander and improved means for preventing undue relative rotation between the spacer-expander and .the rails.

Other objectsand advantages will become apparent as this description progresses and by reference to the drawing wherein- Fig. 1 is a horizontal section through the groove of a piston and illustrating a ring structure embodying 'my invention mounted therein, the ring structure being shown in the condition which it assumes when confined within the cylinder of the engine;

Fig. 2 is an enlarged sectional view of the structure shown in Fig. 1, the same Abeing .illustrated in operative relation to the cylinder wall;

Fig. 3 is a perspective view of a portion of the spacer-expander; and

Fig. 4 is a perspective view of the ends of one of the rails.

The ring is adapted to be mounted in the oil groove l ofra piston 8 of an internal combustion engine. The piston, which may be of any desired structure, is mounted Within. the cylinder Wall 9, as is well understood. i

'Ihe ring structure comprises two flat, thin split rails II and I2, preferably formed of steel, and a spacer-expander designated generally by the reference numeral I3. The rails' II and I2 are split at Ila and I2*i respectively. as shown in Fig. 1. in which the rail II is illustrated broken away to disclose thevend portions of thel rail I2.

'I'he spacer-expander I3 comprises a member of thin spring ribbon or stripnsuch as steel, and is constructed and shaped to space the rails apart and also expand them radially to press the outer peripheries of the rails against the cylinder wall. The spacer-expander is of generally polygonal form having side sections I4 and hump portions l5 between and joining the ends of the side sections. The ends of each side section I4 are slightly bowed outwardly to form shallow curvedl expander is split at the center of one of the humps, as indicated at |33. l

The central portions of the side sections Il seat against the bottom of thering groove I and the vertical .ridges I6 at the ends of the side sections engage the inner peripheries of the rails, the spacer-expander thus acting to expand the rails radially against the cylinder wall. vThe humps I5 project between the rails and serve to space and maintain the rails apart. The edges of the humps I5 are straight'and parallel to each other and also to the adjacent parallel faces of the rails II and I2, so that the spacer-expander does not exert any axial pressure against the sides of the rails.

Each edge of each side lsection I4 is provided with a notch which gradually increases in depth the pistn, back to the crank case of the engine.

The notches also permit the spring side sections.

I4 to flex uniformly -from their central portions to their ends without placing any undue'exing stress at any point throughout the length of the side section. The side sections operate substantially independently of each other as the humps are free to bend as the sides are ilexed during operation of the engine. The contacting area oi each side section I4 with the bottom of the piston. groove is comparatively small, because my structure permits this area to be about one-half of the contacting area of each side section of the conventional form of expander which is entirely located between the ring or rails and the bottom of the piston groove. Thus I provide improved spring action and also ample draining through the drain openings 20 which are .in' portions of the side sections beyond the central contacting area.

It is the practice of some engine manufacturers to machinev -the bottom of the piston groove, and in some instances this operation has resulted in forming a square annular llet or ridge I8 in one or both corners of the groove, as illustrated in Fig. 2. I have found that if the central portions of the side sections I4 of the spacer-expander are rectangular, these portions adjacent their edges seat against the iillet and become twisted or locked in position, with attendant defective operation of the ring. To overcome this difficulty, I bevel the inner corners (as terfere with the spacer-expander. The edges of the humps I5, however, are not beveled, but are horizontal and parallel being so formed whenv the stock is cut away to reduce the Width of the portions forming the humps.

It is desirable to support to a considerable extent the ends of the rails and to also prevent undue rotational movement between the rails and the spacer-expander. To accomplish these ends, I provide on each rail to one side of its joint III or I2* struck-out tabs or lugs 2I and ZIl which extend circumferentially and toward each other and are inclined to the plane of the rail. the rails, the lugs 2| and ZI* of each rail are positioned on opposite sidesof a full hump`I5 of the spacer-expander.A Preferably the lugs of the one'rail are located on both sides of the rst full hump to one side of the joint or split I3*1L and the lugs of the other rail are located on both sides of the first full hump on the other side of the joint I3, as shown in Fig. l. Any undue rotation of the rail with respect to the spacerexpander is prevented as the rounded end of one of the lugs 2I and 2l* strikes the side of the adjacent hump.

I claim:

1. In a piston ring structure adapted for use in a ring groove of a piston of an internal combustion engine comprising a pair of thin rails adapted to be mounted along the opposite sides of the ring groove, the rails being split to provide rail joints and each rail having two projections adjacent the joint, and a spring spacer-expander means having expanding portions adapted to engage the inner peripheries of the ra-ils to expand the same and also having spacing portions extending between the rails to space and maintain the rails apart. the projections on the rails being adapted to engage adjacent spacing portions to prevent material relative movements between the rails and the spacer-expander.

2. A piston ring structure adapted for use in a ring groove of a piston of an internal combustion engine, comprising a pair of thin, flat rails adapted to be mounted along the opposite sides of the ring groove, the rails being split to provide rail joints and each rail having two integral inclined projections, and a spring spacerexpander of ribbon metal having sides, the ends of which are adapted to engage the inner peripheries of the rails to expand the same, and also having humps connecting the ends of said sides and extending between the rails to space and maintain the rails apart, the projections on each rail being adapted to engage adjacent humps to prevent material relative movements between V the rails and the'spacer-expander.

In assembling the spacer-expander andv opposite sides of one of said humps to prevent material relative movement between the rails and the spacer-expander.

4. A spacer-expander for piston ring structure having thin, split rails axially spaced apart with their outer peripheries adapted to engage the cylinder wall, which comprises a thin spring ribbon member having side sections, the central portions of which are adapted to seat upon the bottom of a piston ring groove and the ends of which have outwardly bowed shallow ribs adapted to engage the inner peripheries of the rails to expand the same, and circumferentially spaced portions of reduced width and connecting the ends of the side sections and adapted to extend between the rails to support and maintain the latter in substantially uniform axially spaced relation.

5. A spacer-expander for piston ring structure having thin, split rails adapted to be axially spaced apart in a piston groove with their outer `peripheries adapted to engage the cylinder wall,

which comprises a thin spring ribbon member of generally polygonal shape and having side sections and connecting hump portions, the side sections having central portions with a width but slightly less than that of the piston groove and being adapted to seat upon the bottom of the piston groove, and the side sections having end portions with a width substantially the same as that of the central portions and being adapted to engage the inner peripheries oi the rails, andA the edges of the side sections being provided with staggered notches of gradually increasing depth from the central portions to the end portions with the greatest depth adjacent the end portions to provide uniform spring action and oil drainage, and the hump portions being connected to the ends of the side sections and being of reduced width and adapted to extend between the rails to support and maintain the latter in substantially uniform axial spaced relation.

6. A thin, at, split rail for use with an expanderhaving humps, comprising: an annular 3. A piston ring structure adapted for use in a ring groove of a piston of an internal combustion engine. comprising a pair of thin, flat rails adapted to be mounted along the opposite sides of the ring groove, the rails being split to provide rail joints and each railv having two circumferentially disposed and oppositely extending integral projections inclined to the plane of the rail, and a spring spacer-expander of thin metal having sides, the ends of which are adapted to engage the inner peripheries of the rails. to expand the member having a pair of struck-out circumferentially spaced tabs arranged at an angle relative to the plane of said member and adapted to cooperate with the humps o! an expander to prevent undue relative rotational movement between said rail and expander.

7. A thin, flat, split rail for use with a polygonal expander having humps, comprising: an annular member having a pair of tabs struck out along the inner peripheral edge thereof, said tabs being inclined relative to the plane of said member and converging toward each other, said tabs being spaced suiiiciently far apart circumferentially to receive the hump of an expander therebetween.

8. A piston ring structure comprising a thin, at rail adapted to be'mounted adjacent one side wall of a piston ring groove, said rail being radially split and having a pair of inclined converging tabs struck out along the inner peripheral edge thereof, and a resilient generally polygonal expander element having side portions and humps connecting saidside portions, said side portions being of an axial width slightly less than that of the ring groove in which the same is to be mounted and said humps being reduced invaxial width an amount at least equal to about the axial thickness of said rail, said tabs being spaced apart same, and also having humps connecting the ends of said sides and extending between the rails to space and maintain the rails apart, the projections on each rail being adapted to be located on circumferentially a distance suilcient to receive one of said humps therebetween to prevent undue relative rotation between said rail and expander. l

9.`A piston ring structure comprising a resilient member having side portions and humps connecting said side portions. said side portions having an axial width slightly less than that of the ring groove in which the same is to be mounted, thin at rail means adapted to be mounted adjacent one side wall of the piston ringgroove, said rail means b g radially split and having a.

pair of tabs struck outI along the inner edge thereof and arranged at an angle to the plane o i said rail means, said humps being of less axial width than said side portions by an `amount equal to about the axial thickness o! -said rail means, said tabs being adapted. to cooperate with said humps to prevent undue relative rotation between said expander member and said rail means.

RALPH R. TEETOR. 

